Composition



Patented July 16, 1946 COMPOSITION Milton P. Kleinholz, East Chicago, Ind., assignor to Sinclair Refining Company, New York, N.

a corporation of Maine No Drawing. Application August 9, 1945, Serial No. 609,938

4 Claims.

This invention relates to improved mineral oil compositions particularly effective as turbine or hydraulic oils. It relates more particularly to minera1 oil compositions consisting principally of a. petroleum lubricating oil fraction, the characteristics of the oil being modified by the addition thereto of a small proportion of a semi-lactide of an alpha hydroxy aliphatic acid in which the aliphatic radical contains not less than 10 nor more than 18 carbon atoms.

The semi-lactides of the alpha hydroxy aliphatic acids are formed by condensation of two molecules of the acid with elimination of one molecule of water:

Ron-coon RCHOHCOOH RCHOHCOOH --o (I) O=CCHOHR longed periods without interruption, but usuallyiit must serve as a coolant, to lubricate the gearing mechanism and to operate oil-actuated governors or control mechanisms having very nice tolerances and lubricate other auxiliary equipment.

Many lubricating oil compositions highl satisfactory for the lubrication of other mechanisms have been found to be wholly unsuitable for use as a turbine oil. This is probably due primarily to the fact that in normal use turbine oils rapidly become contaminated with water. Whatever the cause, it is generally recognized thatthe performance of a turbine oil is not predictable from conventional tests applicable to other oillubricants.

Essential characteristics of a satisfactory modern turbine oil include, inaddition to ordinary lubricating requirements, extraordinary resistance to emuisification in the presence of water, and the avoidance of the rusting of metal parts within the oil system of the turbine, and auxiliary apparatus, under operating conditions,

The use of many lubricating oil compositions,

otherwise satisfactory as turbine oils, has re- 5 sulted in the rusting of metal parts within the oil system with consequent serious interference with the operation of the iurbine, including oilactuated governors and other parts. depending upon close tolerances. The results of such rusting not only interfere with the operation of and tendto clog the delicate clearances of the oil system, but the products of the rusting appear to catalyze oxidation of the oil with resultant sludge formation, which ma further aggravate such conditions, The products of the rusting also appear to act as emulsifying agents.

In marine turbine operation, the exacting conditions under which the turbine oil must function satisfactoril are frequently further aggravated by the contamination of the oil with salt water, for instance seawater, which has been found incompatible with many of the corrosion inhibitors previously found suitable as addends for ordinary lubricants, To meet modern turbine oil specifications, particularly Navy specifications, the oil composition must satisfactorily pass, tests involving its contamination with salt water.

The unique requirements of a turbine oil have resulted in the formulation of special test methods for determination of the characteristics of the oil with respect to rusting. The results of rusting tests, hereinafter noted, were obtained in accordance with the method prescribed by the American Society of Testing Materials, procedure ASTM specification D665-42T, and designated Rust-preventing characteristics of steam turbine oil in the presence of water."

In many of the rusting tests, results of which are reported herein, asalt solution was used, as indicated, instead of distilled water prescribed by the test, said salt solution being prepared in accordance with the following Navy formula for synthetic sea water, the proportions being per liter of distilled water:

Grams NaCl 25.0 MgClzSI-IzO 11.0 CaClz Q. 1.2 Na2SO4 4.0

Test conditions when the salt water i substituted for distilled water are much more severe than when distilled water is used in the test, and oil compositions capable of withstanding such conditions have been found suitable for either land turbine or marine turbine use or as hydraulic oils.

As previously indicated, a further essential characteristic of turbine oils is that they do not form objectionable emulsions under conditions of use. Consequently, in the compounding of such oils. it is necessary to avoid the use of addends which might deleteriously affect the emulsibility of the oil.

An acceptable method for determining the emulsifying characteristics of turbine oil is that designated Emulsion test for lubricating oils" prescribed by the "Federal Standard Stock catalog, section IV (part 5) Federal specifications for 3 lubricants and liquid fuels, general specifications (methods for sampling and testing), VV-L-191a, October 2, 1934, method 320.12," conventionally known as Navy emulsion test.

The turbine oil addends of my present invention, though not generally directly effective in inhibiting the oxidation of the oil, have been found to be compatible with many of the known anti-oxidants effectively used in mineral oils, for instance anti-oxidants consisting principally of 2,6-ditertiarybutyl-4-methyl phenol, as the active ingredient, marketed under the trade names Paranox 441 or PX 441" and "GK 3.

A further important characteristic of a turbine oil, particularly one containing a rust inhibitor, is the ability of the rust inhibitor to retain its effectiveness over prolonged periods of use. In addition to the rusting tests previously noted, turbine oils are frequently subjected to a life test, designated R-P life test," which comprises the repetition of the rusting test, using fresh test specimens and fresh salt water but the same oil composition. My improved mineral oil compositions have been found to meet these life tests satisfactorily.

The proportion of semi-lactide used in accordance with my invention may vary over a considerable range, depending primarily upon the severity of conditions under which the oil is to be used and the particular semi-lactide used as the rust inhibitor. Under salt water conditions, advantageous results have been obtained using pro- .portions of the addend within the range of about 0.005% to about 0.10% based on'*-the mineral oil content. Under less severe conditions, even smaller proportions may be used with advantage. Larger proportions may be used, but are not generally required.

.The mineral oil constituent of my improved turbine oils may consist of a petroleum lubricating oil fraction or a blend of oils such as ordinarily specified for turbine oils. It may with advantage be highly refined lubricating 011,; for instance an acid-treated petroleum lubricating oil fraction, or one which has been subjected to 'solvent reflning, for instance a phenol-treated fraction from East Texas crude.

compounding hydraulic oils in accordance with my invention, mineral oil fractions conventionally used for this purpose may be employed. For example, I have used with advantage hydraulic oils obtained from South Texas gas oil by acid treating and compoundingwith a conventional viscosity index improver. Anti-wear agents and antioxidants may also be included. As a turbine oil base oil I have with advantage used, for instance, phenol extracted Mid-Continent neutrals and furfural extracted neutrals produced from San Joaquin Valley crude. The base oil used in the examples subsequently appearing herein was a neutral oil from an East Texas crude, having the following characteristics:

Gravity, API 30 Flash, "F 400 Fire, F 445 Viscosity, at 100 F. SSU 160.5 Vis'cosity, at 130 F. SSU 87.0 Viscosity, at 210 F. SSU 43.4 Pour, F +10 Neut. No 0.00 Carbon residue 0.01 Color 1W4- Percent sulfur 0.09

The semi-lactidesused in the compounding Similarly, in

I vantage be prepared by the self-esteriflcation of the corresponding alpha hydroxy acids. It is not necessary to employ highly refined acid, relatively crude material being satisfactory. Thus,

I have successfully used alpha hydroxy lauric acid prepared from alpha bromo lauric acid as follows:

482 grams (1.73 moles) of the halogenated fatty acid were introduced into a 3 liter balloon flask and refluxed for 6 hours at 220" F. oil-bath temperature with a solution of 285.6 grams (5.1 moles) of potassium hydroxide in 1850 cc, of water. The reaction solution was acidified with 400 cc. of concentrated hydrochloric acid. An organic phase formed and was separated. It was given two acid washes-the first consisting of 300 cc. of concentrated hydrochloric acid in 200 cc. of water, the second of 200 cc. of concentrated hydrochloric acid in 200 cc. of waterand then a. water wash. The crude alpha hydroxy lauric acid was taken up in ether and separated from the aqueous phase. The ether was evaporated at atmospheric pressure and finally under vacuum. A yellowish-white solid was obtained having a neutralization number of 221, a phenol number of 201 and a bromine content of 1.2%.

Alpha bromo lauric acid, suitable for use in the preparation of alpha hydroxy lauric acid is readily produced starting with lauric acid. The following description is illustrative:

2002 grams (10 moles) of lauric acid, analyzing 270 neutralization number, 270 saponification number and 0.2 bromine number, and 103 grams (3%; atoms) of red phosphoru were charged to a 5 liter 3 neck flask, provided with a dropping funnel, reflux condenser, and thermometer, and heated by a steam bath. 3200 grams (20 moles) of bromine were added to the molten acid in 3 hours time,-following which a reaction temperature of 190-195 F. was maintained for 5 hours. The reaction mixture was then allowed to stand at room temperature for about 40 hours, following which it was water washed with 3 liters of water and taken up in 6 liters of benzol. 18.08 lbs. of a 33.75% solution of alpha bromo lauric acid in benzene was obtained. A topped sample, benzene free, analyzed 29.6% bromine.

When I desire to use pure alpha hydroxy lauric acid for the self-esterification, I usually prepare the alpha hydroxy lauric acid by the procedure of the following run:

grams (2.14 moles) of potassium hydroxide and 2000 cc. of water were added to 200 grams of the bromo-fatty acid (prepared as above) in a 3 liter balloon flask and the resultant solution was boiled about 4 hours. It was then acidified with 200 cc. of concentrated hydrochloric acid. The organic phase was taken up in ether and was given an acid wash and two water washes. The ether was evaporated and the residue crystallized twice from chloroform. 8 grams of pure alpha hydroxy lauric acid, a white, crystalline solid, M. Pt. '73-'74 C., was obtained.

The self-esterification of the alpha hydroxy acid with the production of the desired semilactide may be easily effected by heating the acid in the presence of a suitable inert solvent, while providing for the removal of the water resulting from the self-esterification. Toluene is a preferred solvent in the instance of alpha hydroxy lauric acid. Care should be exercised to see that the reaction does not proceed to the extent that substantial amounts of lactide, i. e. in excess of about 20%, are formed, for the lactide, as will be demonstrated subsequently, is without value as a corrosion inhibitor.

the semi-lactide of alpha hydroxy lauric acid cwrimcn -ooou t =-CIl0ll(|nlI:v

I do not attempt to isolate the semi-lactide from the reaction mixture, but use as the addend and t ti of alpha hydroxy la d all of the material remaining upon evaporation CMHCIFFfl) of the inert solvent. The presence of alpha hyi droxy aliphatic acids, in which the aliphatic radi- F cal contains from to 18 carbon atoms, is not 0 v 0=c-cu- ',-u.. objectionable in corrosion inhibitors added to sample A contained the greatest-percentage of hydrocarbon oils, in fact these acids of themthe p tid (38-77%), while Sample C conselves are to some extent effective as corrosion insisged predominantly of 1 Sample 3 was hibitors in yd ca 0118, although when used of intermediate composition. Blends of each of alone they seem to 10 6 p Of their effectiveness the samples in a neutral oil from an East Texas upon storage of the inhibited oil. Also, when Crude were prepared and subjected to the Navy used alone, that is, in the absence of semi-lacticle. salt water emulsion and rust tests, along with they are relatively more prone to cause emulsion blends prepared with unesterified alpha hydroxy difliculties. lauric acid. Results are triven in Table I below:

Table 1 Navy salt rust tests Navy emulsions Nisut Rating 13% H2O NaCl Hydroxy lauric acid 0.015% hydroxy lauric acid 0.02% hydroxy lauric acid. 0.0391 hydroxy lauric acid Hydroxy lauric acid, sc1f-cstcrified 3% hours (sample A) 0.010"; hydroxy lauric acid, sclirsterifiod 3 4 hours... 0.015% hydroxy lauric acid, seli-esterilled 3% hours.. 0.02f31iydroxy lauric acid, scll-cslcrified 3% hours. 0.03% hydrmry lauric acid, scli-cstcrificd 336 hours. 0.050;, hv lroxy lauric acid, sclf-cstcrificd 3 54 hours Hydr v lauric acid, scll-cstcrifiod 13 hours (sample 13).. 0.02% hydroxy lauric acid, scll-estorificrl 13 hours. 0.03% hydroxy lauric acid, self-esterificd 13 hours.. 0.05% hydroxy lauric acid, sclf-estcrificd 13 hours llvdrory lauric acid, sclf-cstcrified 48 hours (sample 0.02"?I hydroxy lauric acid, self-esterificd 48 hours... 0.036 hydrox y lauric acid, sclf-cstcrified 48 hours.

0.05 .1 hydroxy lauric acid, self-csterificd 48 hours I Rust test ratings:

A-Passes test: no rust on strip. B++Traccs of rust on strip. B-l-Up to 5% of surface rusted. 13-5 to of surface rusted. C-25 to 50% of surface rusted. D--50 to 75% of surface rusted. 15-75 to 100% of surface rusted.

My invention is further illustrated by the following example:

Example I Wt. in Total Neutralizaqam 1e grins. of reaction glfi tion number p topped time, of topped sample hours sample 36 i 3% 210247 161 42 l 13 247-259 94 116 I 48 250-205 hydroxy lauric acid cmnzicnoncoon OK" in the last two columns of the table indicates that the oil satisfactorily passed th emulsion test. and the value following the OK," where given, represents the minutes required for the emulsion to break completely.

From the table the progress of the esterification may be followed by the drop in neutralization number. It will be noted that after the 3% hour esterification the product is more effective than the original material, i. e., the unesterified acid, but that there is a progressive loss in effectiveness upon longer heating. Sample C, containing the greatest proportion of lactide, possibly consisting entirely of lactide, will be seen as completely inefiective against rusting.

The composition containing 0.015% of Sample A, equivalent to from about .0057% to .0115% of the semi-lactide of alpha hydroxy lauric acid, represents a preferred embodiment of the invention.

It is to be clearly understood that my invention is not limited to the semi-lactide of alpha hydrox lauric acid, since the semi-lactides of other alpha hydroxy aliphatic acids in which the aliphatic radical contains from 10 to 18 carbon atoms are also effective, e. g. the semi-lactides of alpha hydroxy lauric acid, alpha hydroxy capric acid,

8 proportion of the ,semi-lactide is within the range of about .005% to about 0.10% by weight.

3. An improved mineral oil composition which comprises a petroleum lubricating oil fraction with which there has been compounded a proportion, effective to retard rusting, of the semilactide of alpha hydroxy lauric acid.

4. The composition of claim 3, in which the proportion of the semi-lactide is within, the range 10 of about .0057% to .0115% by weight.

MILTON P. KLEINHOLZ. 

